For a hydrogen-gas tank in a fuel-cell vehicle, there is a need for a safety valve incorporating gas releasing means which includes a fusible member which fuses at higher temperatures and releases gas within a container along with the fusion of the fusible member, in order to prevent the tank from bursting due to a rise of an internal pressure thereof along with a rise of a temperature of the tank. Patent Document 1 discloses a safety valve which is structured to include a main body mounted to a container, a cylindrical-shaped housing coupled to the main body and the gas releasing means and to incorporate the gas releasing means by coupling male screw portions provided in the main body to female screw portions provided in the housing through screws, wherein the safety valve can be mounted to the container by coupling, through screws, male screw portions provided in the main body of the safety valve to female screw portions in the container.    Patent Document Japanese Unexamined Patent Publication No. 2004-263786